Every year, Americans consume nearly 400 million pounds of honey. But less than half of it comes from the United States - with only 148 million pounds produced by American beekeepers last year.

That means, even though many of the jars in the grocery store are labeled "local," on closer inspection that honey may be coming from Argentina, India, Vietnam, Brazil and Canada.

"Local means local to where it's from," said Eric Mussen, apiculturist and leading bee expert at UC Davis.

He recently bought a crate of three oversize squeeze-bear bottles of "local honey" from Costco, peeled back the label and discovered it was actually from Brazil.

Although there's nothing wrong with most imported honey, Mussen said, there have been a few cases of unscrupulous importers trying to slip "junk honey" over the borders - by watering it down with malt sugar, corn syrup and other fillers.

"But most of those guys are in jail now," Mussen said.

In one notorious 2002 case, European and Canadian officials seized more than 80 shipments of Chinese honey that contained the antibiotic chloramphenicol, used by beekeepers to ward off American foulbrood disease in the hives.

Although cases are rare, chloramphenicol has been linked to liver damage, bone marrow suppression, anemia and leukemia in humans, and has been banned for use by beekeepers in the United States.

Adulterated honey, and price undercutting, led the United States to impose a $1.20-per-pound tariff on imported honey in 2002, to raise foreign honey prices to match U.S. ones. Chinese honey in particular fell under extra scrutiny and testing by U.S. customs officials.

The tax precipitated a sharp drop in Chinese honey imports, but an industrious reporter , Andrew Schneider of the Seattle Post-Intelligencer, owned by the Hearst Corp., which also owns The Chronicle, exposed a widespread honey laundering operation in 2008, whereby China sent its honey to neighboring countries for packaging, then on to the United States under the other country's label.

A federal grand jury indicted five companies and 11 individuals in 2010 for trying to pass off Chinese honey as coming from Russia, India, Indonesia, Malaysia, Mongolia, Philippines, South Korea, Taiwan and Thailand. Chinese honey was temporarily banned in the United States.

Next China tried "ultra-filtering" its honey to get the antibiotics out, using a hot pressurizer to push the honey through a porous ceramic filter.

"But not only did it take out the antibiotic, it took out all the pollen, the natural sugars and the color," said Kim Flottum, editor of Bee Culture magazine.

"They ended up with something like sweet syrup. It wasn't honey anymore; the U.S. sent it back."

Today Chinese honey makers are using a different filter that produces a more honey-like product, and has found a market for it in Europe, Flottum said.

"But they really fell off the map here. We aren't importing much of it anymore."

Or you can follow the advice of San Francisco beekeeper Kevin Jones, who puts a sticker on all his jars of Glen Park Wildflower Honey that reads: "How do you know if it's pure honey if you don't know the beekeeper?"